1. Field of the Invention
This invention relates to a portable pen-input computer apparatus capable of operating by power from a battery power source.
2. Description of Related Art
Portable pen-input computer apparatuses capable of operating by power from a battery power source, typically portable pen-input computer apparatuses having a compatibility with the software for the PC/AT series of IBM Corp., are arranged as shown in FIG. 14.
FIG. 14 is a block diagram of a control system of such a conventional pen-input computer apparatus.
A block 9 in FIG. 14 represents a display controller for controlling a display means such as a liquid crystal display (LCD), which is ordinarily a unit called VGA or EGA (registered trademark of IBM). The display controller 9 mainly consists of a display control section 5 and an arbiter 7 for preventing a conflict between an access from a CPU to a VRAM 27 and an access from the display control section 5 (readout). A block 16 represents a peripheral circuit 16 (ordinarily called a chip set) in which an interrupt controller, a direct memory access (DMA) controller, a dynamic random access memory (DRAM) controller and various registers are incorporated by being arranged in accordance with the architecture of the PC/AT series. A block 17 represents a main central processing unit (CPU) for controlling processing of user programs and the like, a block 18 a read only memory (ROM) for storing a basic input output system (BIOS) or the like, and a block 19 a random access memory (RAM) for storing user programs and various kinds of data. A block 12 represents a digitizer controller 12 which controls a digitizer and which transmits detected coordinate data to the main CPU 17. A block 20 represents a clock control circuit for supplying clock to the main CPU 17 and the chip set 16. The clock control circuit 20 has a function of reducing the clock or stopping the clock (for standby) by an instruction from a power management controller 29. An oscillator 21 is connected to the clock control circuit 20 to effect original oscillation of the clock of the clock control circuit 20. A block 22 represents a power supply control circuit for controlling the supply of power to sections or components of the portable pen-input computer apparatus, a block 23 a main battery which is a power source for the pen-input computer, and a block 24 a sub battery provided as a power source for maintaining the memory content of the power management information memory means 15 even if the main battery is removed or the battery energy is dissipated. Switching diodes 25 are provided between the power management information memory means 15 and the main and sub batteries to switch the power supply to the power management information memory means 15. The system also includes a ROM 26 for storing a handwriting recognition routine and a recognition dictionary, a power management window display switch 28 for starting power management processing during the execution of an application program, a power management controller 29 for controlling the power supply for the portable pen-input computer apparatus, and light emitting diode (LED) indicators 30 for indicating the state of the batteries and the state of the CPU operating clock. The operation of changing power management parameters will be described with reference to FIGS. 15 and 16.
FIG. 15 is a diagram showing an example of a power management parameter change window in the conventional portable pen-input computer apparatus. FIG. 16 is a timing chart for explaining the power management parameter change operation in the conventional portable pen-input computer apparatus.
A parameter of power management, for example, with respect to the stoppage of the CPU clock or the operation of turning off the power supply to a peripheral unit consuming a large amount of power, such as a hard disk (HD) or a display backlight, may be changed. As shown in FIG. 16, if a user wants to change an idling time before the CPU is set in a standby state (the CPU operating clock is stopped), i.e., a period of time through which the CPU is allowed to perform no processing while being supplied with the operating clock, and after the elapse of which the operating clock is stopped to set the CPU in a standby state, the power management window display switch 28, which is ordinarily provided on a casing of the pen-input computer, is then depressed to display a power management window such as that shown in FIG. 15, a necessary portion (for changing the time parameter of "CPU STANDBY" in this case) is touched with a pen to change the corresponding parameter, and "EXIT" is thereafter touched to return the operation to the execution of an application program.
Power management information on remaining battery power and other conditions is ordinarily displayed, for example, through a window specially provided for power management as shown in FIG. 15 or a special application program, or is displayed by using a medium such as an LED indicator.
The above-described conventional control system, however, entails problems described below in (1) to (3), since a power management display is made through a special display window, by the execution of a special application program or by using a special display medium (a separate LED indicator or the like).
(1) Each time the display of the special window or the execution of a special application program is made, an application program executed theretofore must be interrupted. Such an interruption may hinder user's thinking process or work. PA0 (2) If a process in which a processing timing is very critical, e.g., a process in accordance with a processing communication program in synchronization with a timer, is being executed in a case as shown in (1), a situation may result where a software compatibility is impaired. PA0 (3) If a power management display is made by using a special display medium such as an LED indicator, a space in which the medium is mounted is required as well as power supply to the medium. The important features of the portable pen-input computer apparatus, i.e., a small size, a light weight and low power consumption, are thereby reduced or impaired, resulting in a reduction in the commodity value.